Update at 10:50 p.m.:

NPR's Peter Kenyon, covering the talks in Lausanne, Switzerland, reports:

"A major compromise that could be part of a deal wold involve Iran agreeing to ship much of its stockpile of nuclear fuel out of the country, presumably to Russia. But Sunday evening, Iranian media quote Deputy Foreign Minister Abbas Araqchi as saying, 'Sending uranium stockpile out of the country is not [on] the agenda.'"

Kenyon says there are other ways to reach the U.S. goal of assuring that Iran's enrichment program is used only for peaceful purposes. But Araqchi's comments may give more ammunition to critics already nervous about a deal with Iran.

Kenyon reports that analysts say this appears to be part of the effort by both sides to gain last minute concessions as Tuesday's deadline for a framework agreement approaches.

In a sign of the urgency of these negotiations, the foreign ministers of Iran, Russia, China, Germany, France, Britain and Secretary of State John Kerry are all now in Lausanne.

Our previous post continues:

Inching closer to the end-of-month deadline for a deal on Iran's nuclear program, major obstacles remain at the table in Switzerland, even as the sides were converging on an agreement to cap and ultimately roll back Tehran's nuclear ambitions, according to reports.

According to The Washington Post, Secretary of State John Kerry, the chief U.S. negotiator, "cancelled an appearance in Boston where he had hoped to attend an event Sunday night and Monday honoring the late Sen. Edward Kennedy."

The Post says: "Kerry and Energy Secretary Ernest Moniz met early Sunday with Iranian Foreign Minister Mohammad Javad Zarif and the head of Iran's atomic energy agency, Ali Akbar Salehi. That was followed by a meeting with U.S. and European diplomats."

Reuters reports that Tehran has said it might be willing to accept fewer than 6,000 nuclear centrifuges and sending its enriched uranium for storage in Russia. In exchange, the West might allow Iran to conduct limited, closely monitored enrichment work for medical purposes.

"We're hopeful, but there is still a lot of work to be done," French Foreign Minister Laurent Fabius told reporters on Sunday, according to Reuters.

Israeli Prime Minister Benjamin Netanyahu, however, has continued to remain firm on his opposition to any such deal.

"The dangerous accord which is being negotiated in Lausanne (Switzerland) confirms our concerns and even worse," Netanyahu said in remarks at a meeting of his cabinet broadcast on public radio, according to Agence France-Presse.

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